Lock mechanism with internal keyhole shutter



E. N. JACOBI June 15, 1954 LOCK MECHANISM WITH INTERNAL KEYHOLE SHUTTER Filed Jan. 25, 1952 2 Sheets-Sheet 1 jwwgz Edward NJTacabz r? My.

E. N. JACOB] LOCK MECHANISM WITH INTERNAL KEYHOLE SHUTTER v Filed Jan. 25, 1952 2 Sheets-Sheet 2 krkivvmr Patented June 15, 1954 LOCK MECHANISM WITH INTERNAL KEYHOLE SHUTTER Edward N. Jacobi, Mil

waukee, Wis., assignor to Briggs & Stratton Corporation, Milwaukee, Wis., a corporation of Delaware Application January 25, 1952, Serial No. 268,300

15 Claims.

This invention relates to lock mechanisms of the type generally used on the doors and rear compartment covers of automobiles and the like, and refers more particularly to the provision of an improved shutter for closing the entrances to the key openings in such looks.

The lock mechanisms herein concerned are of the cylinder type, that is, they are provided with a cylinder having a number of locking tumblers retractable by insertion of a proper key into a key slot in the cylinder to free the cylinder for rotation from a locked to an unlocked position.

Heretofore several different types of closures have been devised for the key openings of such locks. Many of these have been mounted on the exterior of the lock for swinging motion toward and from an operative position covering the entrance to the key opening in the front of the lock, and were commonly known as dust covers. Others have been of the internal type mounted beneath a cap of bright metal covering the front of the lock cylinder. In the latter instance, of course, the cap is provided with a key opening registering with the key slot in the cylinder, and the shutter closes the key opening from the rear of said cap.

This invention is concerned with key hole shutters of the internal type, wherein the lock cylinder has a cap covering its front end and the shutter is pivotally mounted on the front of the cylinder beneath the cap.

One of the major problems encountered in connection with key hole shutters of this type is that of friction in the shutter bearings. Whenever friction not readily overcome by the shutter biasing spring, there is danger that the shutter will not tightly seal the key opening in the wall of the cap covering the front of the cylinder.

It is one of the objects of this invention, therefore, to provide an improved manner of journalling a key hole shutter of the character described on the cylinder of a lock and which will minimize friction to such an extent as to at all times assure proper closure of the shutter by its biasing spring.

More specifically it is an object of this invention to provide a particularly novel manner of mounting a key hole shutter on the front end of a lock cylinder, behind the cap covering the same, which eliminates the need for the customary hinge pin, and by which the shutter is substantially freely suspended in a cavity in the front of the lock cylinder. This is accomplished through the provision of a torsion spring anchored to the lock cylinder and having the key hole shutter of this invention so connected therewith that it is substantially freely suspended by the spring while being guided for pivotal motion to its open position by cooperating bearing surfaces on the shutter and the cylinder normally disengaged from one another in the closed position Of the shutter.

view taken through Figure 1 along the plane of Other objects of this invention reside in the provision of a key hole shutter of such compact nature that it enables a reduction in the diameter of the front of the lock cylinder and associated lock mechanism without lessening the margin of sealing surface around the key hole; and which entails fewer parts shaped to have less friction than was possible in the past. In addition it is a purpose of this invention to provide a low cost key hole shutter which is readily installed in the front of the lock cylinder and held in place by the securement of the cap to the front of the cylinder.

With the above and other objects in view, which will appear as the description proceeds, this invention resides in the novel construction and arrangement of parts substantially as hereinafter described, and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereinafter disclosed invention may be made as come within the scope of the claims.

The accompanying drawings illustrate two complete examples of the physical embodiments of the invention constructed in accordance with the best modes so far devised for the practical application of the principles thereof, and in which:

Figure l is a view partly in side elevation and partly in longitudinal section, illustrating a cylinder type lock equipped with the key hole shutter of this invention;

Figure 2 is a front View thereof with portions broken away and shown in section;

Figure 3 is an enlarged fragmentary sectional the line 33 and showing the shutter in a closed position;

Figure 3A is a view similar to Figure 3 but showing the shutter in an open position.

Figure 4 is an enlarged fragmentary sectional View taken through Figure 1 along the plane of the line l4;

Figure 5 is a group perspective view showing the front of the lock cylinder per se and the shutter removed therefrom;

Figure 6 is a view similar to Figure 4 but showing a modified embodiment of the invention; and Figure 7 is a perspective view of the shutter assembly shown in Figure 6.

Referring now more particularly to the accompanying drawings in which like numerals designate like parts throughout the views, the numeral 5 generally designates :a lock mechanism of the type having a cylinder 5 rotatable inside a casing l with the front end 8 of the cylinder projecting forwardly out of the lock body 6 in which the cylinder and casing are mounted. For the purposes of this invention, however, the cylinder 6 may terminate flush with the front of the lock n need not extend a distance forwardly thereof in the manner shown in Figure 1.

In the customary manner, the lock cylinder 6 is held against rotation in its casing l by tumblers or the like, not shown, and is released for rotation in the casing by insertion of a proper key I 1 into the cylinder from its front end. The cylinder, of course, has a key slot [2 extendin axially therein to receive the key H, and the key slot is enlarged at the front of the cylinder to provide a relatively large forwardly opening cavity i3 therein. The mouth of this cavity is covered by the end wall Id of a cup-like cap ii, of stainless steel or other bright metal, fixed on the front end of the cylinder in any suitable manner.

In the present case, the portions of the front face of the cylinder surrounding the cavity are slightly concave, and the end wall M of the cap is likewise concave so as to have a convex rear surface in intimate engagement with the under lying portions of the cylinder. The end wall M also has a substantially rectangular key opening- I6 therein aligning with the key slot 62 in the cylinder to enable insertion of the key Ii thereinto, and it is this opening which is adapted to be closed by the key hole shutter 13 of this invention.

The shutter is a stamping, preferably of stainless steel, and comprises a flap portion it of slightly concave shape so as to conform to the convexity of the underside of the wall id of the cap with which it engages, around the edges of the key opening it therein, to effectively close and seal said opening. The shutter includes a flat mounting leg 23, integral with the flap por-- tion [9, but bent slightly rearwardly therefrom to define an obtuse angle therewith.

The mounting leg 26 has an elongated medial notch 2| in its side, and is formed with endwise aligned pilots 22 projecting into the notch from opposite ends thereof. On its outer ends the leg 28 has trunnions 23 bent rearwardly therefrom, and of semi-circular shape as seen best in Figures 4 and so as to have convex rearwardly facing rocker-like edge portions. It is important to note that the sides of the trunnions 23 are parallel to one another and that their convex edge portions are coaxial with the pilots 22, though spaced a slight distance outwardly from the adjacent ends of the flap portion IQ of the shutter.

The shutter is received in the cavity iii in the front of the lock cylinder with its leg 2&3 projecting laterally and rearwardly away from the key opening to overlie a forwardly facing ledge 25 in the cavity adjacent to one long side of the key opening and extending transversely of the axis of the lock cylinder lengthwise of the key opening. This ledge comprises the bottom of a step in the side of the cavity, and the ends of the ledge terminate in axially aligned bearing sockets 27 near the periphery of the cylinder, at substantially diametrically opposite side thereof. The bottoms of these bearing sockets face forwardly and are concave, though slightly larger in diameter than the convex edges of the trunnions 23 on the key hole shutter. The concave surfaces of the bearings sockets, of course, are coaxial with one another and the sockets loosely receive the trunnions 23. of the shutter to guide the swinging motion of the shutter as it moves from closed to open positions as seen in Figures 3 and 3A, respectively.

It is important to note that only the opposite extremities of the mounting leg which have the trunnions 23 thereon project into the bearing sockets 27, and the sockets are shallow enough to permit the flap portion i9 of the shutter to swing freely back and forth in the cavity l3, laterally outside of the sockets 21.

From the description thus far it will be apparent that the endwall i i of the cap it holds the'key' hole shutter l3 with its trunnions 23 loosely confined in the bearing sockets 21 for free pivotal motion of the key hole shutter, about an axis normal to the axis of the cylinder, to and from the closed and open positions of the shutter seen in Figures 3 and 3A. The shutter, however, is yieldingly held inits closed position by a torsion spring generally designated 29.

The torsion spring 28 is of special, double wound construction, having helical convolutions defining spaced coaxial sets of coils 39 overlying the ledge 25 and received in the notch 2| in the mounting leg of the shutter to encircle the pilots 22 thereon. The opposing inner convolutions of the coils are extended laterally inwardly, as at 28, of the cap, and project into the cavity behind the flap portion 59 of the shutter. The extensions, 28, however, are integrally joined together at a pointslightly beyond the location of a central rounded pad 3| on the back of the flap portion of the shutter,and' provide a doubled spring arm which bears upon the pad 3! to yieldingly hold the shutter closed.

The coils EB of the spring are preferably yieldingly biased apart to bear against the ends of the notch 2i in the mounting leg of the shutter at the bases of the pilots 22 thereon, and the remote convolutions of the coils are extended laterally outwardly, away from the flap portion of the shutter, to be received in shallow, close fitting parallel grooves 33 in the front of the cylinder extending at right angles to the axis about which the shutter swings. These outward extensions 32 have hooks 34' extending rearwardly therefrom into short longitudinal grooves 35 in the sides of the lock cylinder formed as continuations of the grooves 33 in the front thereof. The bottoms 36 of the longitudinal grooves thus provide abutments engaged by the hooks 3G to preclude bodily shifting of the torsion spring laterally inwardly into the cavity i3. Inasmuch as the grooves 33 and 35 are relatively narrow and shallow, the portions of the front and side walls of the cap 15 overlying the grooves substantially anchor the outward extensions and the coiled portions of the spring in place on the front of the cylinder with the coils 3!? of the spring supported by the ledge 25 against the reaction of the force exerted by the doubled spring arm upon the pressure receiving central pad 3| of the shutter.

Inasmuch as the two coils 38 of the spring are thus held coaxial with one another andwith the bearing sockets 2'5," will be seen that the spring serves to substantially loosely suspend the key hole shutter thereon with the fiat outer surfaces of the trunnions 23 clearing the adjacent ends of the bearing sockets. Moreover, in the absence of any rearward thrust upon the shutter such as is imposed thereon by insertion of the key through the key opening is to swing the fiap portion rearwardly to open position, the forward biasing force exerted on the flap portion of the shutter by the torsion spring substantially lifts the trunnions off of the concave bearing surfaces of the sockets 2? to minimize or practically eliminate friction which along the rear of the end wall [4,

otherwise might interfere with full closure of the shutter. Hence, in the closed position of the shutter, seen best in Figure 4, the convex edges of the shutter trunnions are spaced slightly forwardly of the concave bottoms of the sockets 21.

In other words, the key hole shutter of this invention is somewhat loosely and tiltingly pivotally carried by the torsion spring so that it has sufficient self-adjusting motion relative thereto as to be capable of seating itself perfectly against the convex rear surface of the bottom wall M on the cap, entirely around the edges of the key opening [6 therein, so as to seal said opening against the ingress of dirt, moisture or other foreign matter into the front of the cylinder through said open ing.

It will also be apparent that the trunnions 23 on the shutter and the bearing sockets 2? in which the trunnions are received primarily act to guide the rearward swinging motion of the shutter by the key I l as the latter is inserted into the cylinder. During key insertion, therefore, the force of the key on the flap portion [9 on the shutter effects engagement of the convex bearing surfaces on its trunnions with the concave bottoms of the bearing sockets 21 so that the rearward swinging of the shutter flap is guided with a minimum of surface to surface contact between the trunnion edges and the bearing sockets.

The limited engagement between the free end of the torsion spring and the shutter flap afforded by the pad 31 on the back of the flap, of course, assures freedom of the shutter to tilt as much as necessary to seat properly against the underside of the wall I4 on the front of the cylinder.

In the modified embodiment of the invention shown in Figures 6 and 7 the mounting leg 23 of the shutter is provided with tongues 53? projecting from the opposite ends of the leg coaxially of the pilots 22'. Washers 3'8 nonrotatably received on these tongues project edgewise into the bearing sockets to provide for guiding the rearward swinging motion of the shutter flap to open position, in a manner equally as effective as the trunnions 23 of the previous embodiment of the invention. In all other respects the key hole shutter is the same as that shown in Figures 1 to inclusive. I

From the foregoing description taken togetherwith the accompanying drawings, it will be readily apparent to those skilled in the art that the key hole shutter of this invention is mounted in the front of the lock cylinder in a manner which not only eliminates the customary shutter pivot pin previously embedded in the front of the lock cylinder, but also assures self-centering of the shutter in its closed position and minimizes friction which might tend to cause binding of the shutter and improper closure of the same due to such friction.

What I claim as my invention is:

1. Lock mechanism of the character described, comprising: a lock cylinder having a cavity therein opening to its front end, and having an axial key slot extending rearwardly from said cavity; a Wall on the front of the cylinder covering the mouth of the cavity therein, said wall having a key opening therein registering with the key slot in the cylinder; a shutter in said cavity for closing the key opening in said wall from the rear thereof; means mounting the shutter on the cylinder for swinging motion in said cavity to and from an operative position engaging rear portions of said wall surrounding the key opening therein to close the same, said means comprising forwardly opening bearing sockets in the front of the cylinder adjacent to side wall portions of the cavity therein and spaced apart along a common axis crosswise of the cylinder axis, and trunnion means on the shutter received in said sockets to provide for swinging motion of the shutter about said axis crosswise of the cylinder axis; and spring means on the front of the cylinder behind said wall acting on the shutter to yieldingly hold the same in its operative position closing the key opening in said wall.

2. The lock mechanism set forth in claim 1 wherein said bearing sockets in the front of the cylinder have forwardly facing concave bottoms, and said trunnion means are loosely received in said bearing sockets and have rearwardly facing convex surfaces thereon cooperable with the concave bottoms of the sockets to provide for swinging motion of the shutter about an axis crosswise of the cylinder axis; and further characteristized by the fact that said spring means urges the shut ter bodily forwardly toward its operative position closing the key opening in said wall and tends to hold the trunnions moved slightly out of engagement with the concave bottoms of the bearing sockets to thus minimize friction therebetween during swinging of the shutter from open to closed positions.

3. The lock mechanism set forth in claim 2 further characterized by the provision of a connection between said spring means and the shutter whereby the spring means tends to hold the shutter floatingly suspended in the cavity in the front of the lock cylinder and spaced from the walls defining said cavity to minimize friction between the shutter and the adjacent surfaces of the lock cylinder during spring propelled closure of the shutter.

4. The lock mechanism set forth in claim 1 wherein said sprin means is a torsion spring anchored to the front of the lock cylinder and having helically wound convolutions coaxial with the bearing sockets in the front of the cylinder and received in a notch in one side of the shutter; and further characterized by the fact that the shutter is provided with pilots thereon projecting toward one another from the ends of said notch, coaxial with said bearing sockets and extending into the convolutions of the torsion spring so that the shutter is substantially suspended in the cavity in the front of the cylinder by the convolutions of the spring.

5. Lock mechanism of the character described, comprising: a lock cylinder having a cavity therein opening to its front, and having an axial key slot extending rearwardly from said cavity; a wall on the front of the cylinder covering the mouth of the cavity therein, said wall having a ke opening therein in line with the key slot in the cylinder; a shutter in said cavity having a flap portion engageable with the rearside of said wall around the key opening therein to close the same; a torsion spring carried by the cylinder and having a free end portion bearing against said flap portion of the shutter to yieldingly hold the same in its operative position closing the key opening in said wall; and cooperating means on the torsion spring and the shutter interengaged with one another to pivotally mount the shutter on the spring for swinging motion relative to the cylinder about an axis normal to that of the cylinder to enable the flap portion of the shutter to swing rearwardly away from its operative position in consequence of insertion of a key throughthe key opening in said wall.

6. The lock mechanism set forth in claim 5, further characterized by the provision of other cooperating means on the shutter and the cylinder for guiding said pivotal motion of the shutter.

7. The lock mechanism of claim wherein said cooperating means comprises elements on the shutter and spring having loose engagement with one another to provide for a limited degree of tilting motion of the shutter relative to the spring, by which the flap portion of the shutter is selfadjusting to properly seat against the rear side of said wall entirely around the key opening therein to close the same.

8. The look mechanism set forth in claim 7, further characterized by the provision of a rounded projection on the rear of the flap portion of the shutter against which the free end portion of the torsion spring bears to bias said flap portion forwardly without interfering with self-adjr2stlng motion of the shutter during seating of its flap portion against the rear side of said wall,

9. In a lock of the character described: a rotatable lock cylinder having a cavity therein opening to the front of the cylinder, and having a key slot therein extending rearwardly from said cavity; a wall on the front of the cylinder covering the mouth of the cavity therein, said wall having a key opening therein aligning with the ke slot in the cylinder; means defining a ledge in the cavity at one side thereof, said ledge facing the rear side of said wall but being spaced rearwardly thereof and to one side of the key opening therein; a shutter in said cavity having a flap portion engageabl with the rear side of said wall around the key opening therein to close the same, and having a leg overlying said ledge; a torsion spring on the front of the cylinder, behind said wall, acting upon the shutter t0 yieldingly hold the flap portion thereof in an operative position engaged with the rear side of said wall and closing the key opening therein, said torsion spring having helically wound convolutions circumferentially seated upon said ledge with the axis of the convolutions wholly to one side of the key opening in said wall; means connecting the spring with the cylinder to preclude lateral and axial shifting of the convolutions of the spring; and means on said leg of the shutter engaged with the convolutions of the spring to pivotally mount the shutter thereon for swinging motion of the fiap of the shutter in said cavity toward and from said operative positions thereof, about the axis of said convolutions of the spring.

10. The lock set forth in claim 9 further characterized by the provision of cooperating means on said leg of the shutter and the cylinder for guiding the pivotal motion of the flap portion of the shutter away from its operative position.

11. In a lock of the character described: a rotatable lock cylinder having a cavity therein opening to the front of the cylinder, and having a key slot therein extending rearwardly from said cavity; a cup-like cap on the front portion of the cylinder having a wall extending across the front face of the cylinder, in contact therewith, and covering the mouth of said cavity, said wall having a key opening therein aligning with the key slot in the cylinder; a shutter in said cavity having a flap portion engageable with the rear side of said wall around the key opening therein to close the same; a double wound tercomprising:

8. sion spring havin axaill aligned right and left helically coiled portions in' said cavity at one side of said key opening, the remote convolutions of said coils having outward lateral extensions thereon confined in close fitting relatively shallow grooves in the front of the cylinder by said wall covering th same, and having hooks on their outer extremities engaging abutments on the cylinder so that bodily shifting of the torsion spring is precluded, and the adjacent convolutions of said coils having inward lateral extensions thereon projecting into said cavity and bearing against the back of the flap portion of the shutter to yieldingly hold the same in an operative position against the rear side of said wall, closing the key opening therein; and a, connection between the shutter and the torsion spring mounting the flap portion of the shutterfor swinging motion in said cavity substantially about the axis of said coils of the spring.

12. The lock set forth in claim 11 further characterized by the fact that the coiled portions of the torsion spring are received in a stepped portion of the cavity which provides surfaces against which the coils of the torsion spring seat upon rearward swinging of the flap portion of the shutter in consequence of insertion of a key through the key opening.

13. The lock set forth in claim 11 further characterized by the provision of cooperating means on the shutter and the cylinder for guiding the swinging motion of the flap portion of the shutter from closed to open positions.

14. Lock mechanism of the character described, a lock cylinder having a cavity therein opening to its front end, and having an axial key slot extending rearwardly from said cavity; a wall on the front of the cylinder covering the mouth of the cavity therein, said wall having a key opening therein registering with the key slot in the cylinder; a shutter in said cavity for closing the key opening in said wall from the rear thereof; means mounting the shutter on the cylinder for swinging motion in said cavity to and from an operative position engaging rear portions of said wall surrounding the key opening therein to close the same, said means comprising forwardly opening bearing sockets in the front of the cylinder at one side of the cavity therein and spaced apart in a direction crosswise of the cylinder axis, and washers connected to said shutter and received edgewise in said hearing sockets to provide for swinging motion of the shutter about an axis crosswise of the cylinder axis; and spring means on the front of the cylinder behind said wall acting on the shutter to yieldingly hold the same in its operative position closing the key opening in said wall.

15. The lock set forth in claim 9 further characterized by the fact that the convolutions of the spring are confined in a notch in said leg of the shutter with the remote convolutions bearing against the ends of the notch; and wherein said means on the shutter leg by which the shutter is pivotally mounted on the spring comprises pilots on said leg projecting toward one another from the ends of the notch and extending into the end convolutions of the spring.

Name Date Schwartz June 18, 1901 Number 

